The novel slip prevention device for ladders ensures that ladder feet are completely prevented from slipping. It is particularly suitable, also, for stairs if the feet of the lean-to ladder are placed, for example, immediately at the edge of steps because the ladder is leaning against a wall parallel to the rise of the steps.
Moreover, the slip prevention device may be fitted at the top region of the ladder and may be used as a wall support or as a roof support equipped with load-distributing bars.
The novel slip prevention device can be swung in completely parallel to the outer sides of the ladder-stringer.
On ladders of which the rungs are led through the ladder stringers and are thus open, it is her provided, in order to fasten the slip prevention device, to lead split spindles through the rung cavities from the respectively opposite sides and to screw them to one another within the ladder rungs. Centering cones on the outer sides of the split spindles allow fixed play-free bracing on all shapes and sizes of ladder rungs.
This means that the novel slip prevention device can be reliably retrofitted on all metal ladders irrespective of the make, ladder width, rung shape or rung size.
In order to prevent feet of a ladder leaning against a wall from slipping, the ladder feet are equipped with profiled rubber elements or ground spikes.
In many cases, a second person stands at the ladder foot and secures the ladder against slipping by blocking the ladder feet against slipping using his/her own feet.
As a result of local situations, it is not always possible to comply with the correct positioning angle of the lean-to ladder.
At present, it cannot be ensured that slipping of the feet of lean-to ladders is completely ruled out.
The object of the present invention is to provide a slip prevention device for ladders which overcomes the above-noted deficiencies and disadvantages of the prior art devices and methods of this general kind, and which ensures that the ladder feet are prevented from slipping even in very critical lean-to situations.
With the foregoing and other objects in view there is provided, in accordance with the invention, a slip prevention device for ladders with hollow ladder-rung profiles, wherein the slip prevention device comprises a pair of support guides, which in an articulated manner can firmly be braced on the ladder by means of divisible length-adjustable fastening spindles irrespective of the ladder width and rung geometries. It can further be folded in parallel to the longitudinal direction of the ladder, wherein every support guide includes a support which can be fully extended and secured in both longitudinal directions of the support guides. Every support guide is designed such that it is lockable on the ladder at various angles by a pull/push rod and is pivotable from the lean-to side/rear side to the front side/climbing side of the ladder.
The support guides are each fastened in an articulated manner on the threaded ends of the fastening spindles by a branching-off protrusion, wherein a threaded end on one side belongs to a threaded rod which can be screwed to a threaded bushing arranged on the opposite side and located within the ladder-rung. The threaded bushing is connected firmly to a centering cone, on the outer side of which a threaded bolt is located, wherein on a threaded rod arranged opposite a displaceable second centering cone is disposed, which can be secured by a nut.
Every pull/push rod is fitted by way of one end on a sleeve which can be displaced and secured, surrounding the corresponding support guide, and the opposite end of the pull/push rod being controllable at the projecting threaded ends of a further length-adjustable fastening spindle which can be introduced in a second ladder rung, and be braced with the aid of threaded rods, threaded bushings and centering cones, in a way that the pull/push rods are positioned in a space between the support guides and the ladder.
In one preferred embodiment of the slip prevention device for ladders according to the invention, the fastening spindles may be braced with a ladder-rung profile in a backlash-free manner.
In a further preferred embodiment of the slip prevention device for ladders according to the invention, the support guides and the supports are curved.
In another preferred embodiment of the slip prevention device for ladders according to the invention the sleeves are accordingly curved.
In a further preferred embodiment of the slip prevention device for ladders according to the invention, a length-adjustable auxiliary rod is located between the support guides.
In a further preferred embodiment of the slip prevention device for ladders according to the invention, the pull/push rods are also of length-adjustable design.
In a further preferred embodiment of the slip prevention device for ladders according to the invention, a load-distributing bar is attached to the supports in an articulated manner.
In a further preferred embodiment of the slip prevention device for ladders according to the invention, the load-distributing bar is angled at the ends. In an additional preferred embodiment of the slip prevention device for ladders according to the invention, the load-distributing bar includes supporting rollers.
In a further preferred embodiment of the slip prevention device for ladders according to the invention, a tension spring is located between the load-distributing bar and a support in a way that the load-distributing bar is retained in the swung-in position parallel to the outer side of the ladder.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a slip-prevention device for a ladder, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.